Lou Groen, who owned the first McDonald's restaurant in Cincinnati, Ohio, came up with the idea of a Filet-O-Fish sandwich in 1962, when he was making next-to-nothing on Fridays, according to McDonald's archivist Mike Bullington. He created a Filet-O-Fish recipe and took it to headquarters, where McDonald's chief Ray Kroc was also preparing his own meatless alternative, Bullington said.

Kroc challenged Groen to a Friday sell-off to see whether customers preferred Kroc's Hula Burger, which consisted of a piece of grilled pineapple and cheese on a bun, or the Filet-O-Fish. Bullington said Groen won by a landslide, with the Hula Burger selling six sandwiches and Filet-O-Fish selling 350.